Cell communication

Protection against osmotic or mechanical rupture. The walls of neighboring cells interact in cementing the cells together to form the plant. Channels for fluid circulation and for cell-cell communication pass through the walls. 

The abundance of many protein kinases in cells is an indication of the great importance of protein phosphorylation in cellular regulation. Exactly 113 protein kinase genes have been recognized in yeast, and it is estimated that the human genome encodes more than 1000 different protein kinases. Tyrosine kinases (protein kinases that phosphorylate Tyr residues) occur only in multicellular organisms (yeast has no tyrosine kinases). Tyrosine kinases are components of signaling pathways involved in cell-cell communication (see Chapter 34). 

Cells communicate with each other in order to form and maintain the vertebrate body. Cells must know when and where to move, and what to do once they get there. This is accomplished by sending and receiving chemical, tactile, and perhaps even electrical signals (Cooper and Schliwa, 1986). Cells can be observed responding to at least some of these environmental cues in tissue culture, and also responding to each other. The response of cells to these factors is known as cell behavior. 

Certain proteoglycans (eg, heparan sulfate) are associated with the plasma membrane of cells, with their core proteins acmally spanning that membrane. In it they may act as receptors and may also participate in the mediation of cell growth and cell-cell communication. The attachment of cells to their substramm in cul-mre is mediated at least in part by heparan sulfate. This proteoglycan is also found in the basement membrane of the kidney along with type IV collagen and laminin... 

Pain sensation is modulated by glial cells communication with neuronal cells (reviewed by Scholz and Woolf 2007). The involvement of the CX3CL1/CX3CR1 pair in pain modulation has been recently demonstrated in different examples of experimental neuropathic pain induced by peripheral nerve injury or inflammation... 

WOLF G (1992) Retinoids and carotenoids as inhibitors of carcinogesesis and inducers of cell-cell communication. Nutr Revs 50(9) 270-74. 

DNA damaging mutagenic, elastogenic and cell-cell communication inhibitory properties of y-oryzanoL . 1 Toxicol Sci. 16 191-202. 

Edgar What about lateral inhibition in neuroblast determination This generates asymmetry that is presumably not dependent on any cell division. This is not intrinsic it relies on cell communication. There must be countless examples of this kind of asymmetry being set up. 

Connexin 43 is one of the cell membrane gap junction proteins that allow for cell to cell communication. Cancer cell transformation is correlated with the loss of Connexin 43 expression (Hussain et al. 1989, Zhang et al. 1992). Lycopene increased Connexin 43 expression in fetal skin fibroblasts (Stahl et al. 2000), oral cancer KB-1 cells grown in organotypic rafts (Livny et al. 2003) and breast cancer cell lines (Chalabi et al. 2007). 

FIG. 2.7. Illustration of the way in which multi-cellular organisms combine their cells physically through extracellular connective tissue, often calcified, to give shape and developed cell-cell communication through elements and chemicals. Note that all this evolution was made possible by oxidation following inevitably from the release of 02... 

Extra-/Intra-cell communication Many novel Ca2+ trigger proteins (see Table 9.9)... 

Roshchina, V.V. (1999). Mechanisms of cell-cell communication. In Allelopathy Basic and Applied Aspects. (Ed. S.S. Narwal). Vol. 2 3-25. Science Publishers, Enfield, Plymouth, USA. 

PassadorL, Cook JM, GambelloMJ, Rust L and Iglewski BH. 1993. Expression of Pseudomonas aeruginosa virulence genes requires cell-to-cell communication. Science 260 1127-1130. 

The biosynthetic, secretory pathway is responsible for protein sorting and delivery and allows, among other functions, for cell-cell communication through secreted products. This delivery process starts at the endoplasmic reticulum (ER), to finish in the cell plasma membrane or, in some cases, in specific intracellular organelles. To accomplish this, specific proteins must be properly directed to the correct destination, while other proteins are retained as residents within specific organelles along the way. 

In the last decade, the roles of stem and progenitor cells in the differentiation of the embryonic nervous system have become illuminated, leading to fundamental advances in our knowledge of the regulation of cell fates in the brain. Much is still needed for us to understand the interplay between genetic and cell communication events that leads to normal generation of the complex nervous system. These issues are important to resolve if we are to learn how disease or trauma affect the growing brain. 

The account is primarily focusing on multi-protein signaling cascades, while other pathways are not discussed in detail, and only mentioned to illustrate their position in the colorful world of cell to cell communication. 

Young. I think gap junctions are very important in the initiation of labour. It has been shown that they increase the conduction rate of the action potential prior to the onset of labour. They seem to be induced prior to the initiating event in labour. You can have the gap junctions and the rapid action potential propagation, yet no spontaneous labour. Therefore they are necessary, but not sufficient. If I look at intercellular waves, as I flow the solution across, there is about a five cell communication that goes against the flow. In other words it has an intracellular mechanism, and it seems to be about four or five cells that go against the flow and the rest go with the flow. 

Shepherd VA, Goodwin PB. Seasonal patterns of cell-to-cell communication in Chara corallina Klein ex Willd. 1. Cell-to-cell communication in vegetative lateral branches during winter and spring. Plant Cell Environ 1992 15 137-150. 

The final chapter is dedicated to the state-of-the-art methods for determining lectin affinity and specificity for oligosaccharides. These play a key role in many biological processes relevant to cell communication and disease states, and are involved in cancer development and metastasis, inflammation and host-pathogen recognition. 

For mechanistic studies, cells and their secretory products can be systematically studied in isolation and in various combinations to assess their interactions and cell-to-cell communications. 

Jaenicke L, Starr RC (1996) The lurlenes, a new class of plastoquinone-related mating pheromones from Chlamydomonas allensworthii (Chlorophyceae). Eur J Biochem 241 581-585 Janowitz GS, Kamykowski D (2006) Modeled Karenia brevis accumulation in the vicinity of a coastal nutrient front. Mar Ecol Prog Ser 314 49-59 Joint I, Tait K, Callow ME, Callow JA, Milton D, Williams P, Camara M (2002) Cell-to-cell communication across the prokaryote-eukaryote boundary. Science 298 1207 Kinzie RA (1974) Experimental infection of aposymbiotic gorgonian polyps with zooxanthellae. J Exp Mar Biol Ecol 15 335-342... 

Not all of the newly-synthesised PAF is released by neutrophils it is thought that release of PAF only occurs after a critical intracellular concentration has been reached even then, some PAF remains cell associated and does not act as a true extracellular effector molecule. The cell-associated PAF may thus play a role in cell-cell communication (e.g. neutrophil-neutrophil or neutrophil-endothelium interactions). Intra- and extracellular Ca2+ levels regulate both the biosynthesis and release of PAF. Increases in intracellular Ca2+ may allow PAF synthesis (but not release), whereas extracellular Ca2+ increases both synthesis and release in a dose-dependent manner. 

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